Airports are VERY expensive capital projects.
They maybe but given the opportunity of getting some revenue when facility is already open or gaining nothing then option of gaining something is what they will seek.
Its a no lose situation for Canaries as their passenger numbers are struggling and adding 800,000 tourists where money fed directly into Islands economy will be welcomed.
Utimately too many airport operators are over spending on capital investment and forgetting that majority of people want to get in and out of an airport as quickly as possible with the minimum of hassle.